From the European Published Patent Application No. 0 661 446, a fuel injector having an integrated spark plug is known. The fuel injector with integrated spark plug is used for the direct injection of fuel into the combustion chamber of an internal combustion engine and for igniting the fuel injected into the combustion chamber. Due to the compact integration of a fuel injector with a spark plug, it is possible to save installation space at the cylinder head of the internal combustion engine. The known fuel injector with integrated spark plug has a valve body which, together with a valve-closure member able to be actuated by means of a valve needle, forms a sealing seat, adjacent to which is a spray-discharge orifice, which discharges at an end face of the valve body facing the combustion chamber. A ceramic insulation element insulates the valve body from a housing body in a high-voltage proof manner, the housing body being able to be screwed into the cylinder head of the internal combustion engine. Located on the housing body is a ground electrode in order to form an opposite potential to the valve body acted upon by high voltage. In response to a sufficient high voltage being applied to the valve body, a spark arc-over occurs between the valve body and the ground electrode connected to the housing body.
However, a disadvantage of the known fuel injector with integrated spark plug is that the location of the spark arc-over is not defined with respect to the fuel jet spray-discharged from the discharge orifice, since the spark arc-over may occur at just about any point in the lateral region of a projection of the valve body. In this known design a reliable ignition of the so-called jet root of the fuel jet spray-discharged from the spray-discharge orifice is not possible with the required reliability. However, a reliable and temporally precisely defined ignition of the fuel jet is absolutely required to achieve reduced emissions. Furthermore, the discharge orifice of the fuel jet may be subject to continually worsening carbon fouling or coking, which influences the shape of the spray-discharged jet.